Joint strip consisting of glass fibres

ABSTRACT

The invention relates to a joint tape, in strip form, formed by an open-mesh glass fiber warp knit fabric or woven fabric, said warp knit fabric or woven fabric comprising fibers parallel to the length of the strip and fibers perpendicular to the length of the strip, said tape being characterized in that at least one glass fiber, referred to as reinforcing fiber, parallel to the length of the strip and located in the central zone thereof, has a linear density at least five times higher than the linear density of the other fibers.

The present invention relates to glass fiber joint tapes, particularly suitable for the jointing of boards in the corners.

It is known to use glass fiber meshes as jointing elements between two plasterboards or between a plasterboard and other construction elements. These glass meshes are sometimes self-adhesive. They are put in place and bonded overlapping the joining zone between two adjacent plasterboards, then are generally covered with plaster.

When the plasterboards or construction elements form, with respect to one another, an angle significantly lower than 180°, the easy application of the joint tape requires prior folding thereof in the length direction. However, the elasticity of the glass fibers makes folding the tape along the median line difficult. The tape spontaneously has a tendency to return to its initial flat form. This tendency could, certainly, be reduced by using thinner glass fibers, but only at the expense of a reduction in the mechanical strength properties.

The idea at the heart of the present invention was to facilitate the longitudinal folding of a joint tape by “guiding” it owing to one or more reinforcing fibers, located on the median line or in the immediate vicinity thereof. These longitudinal, reinforcing fibers give the tape good rigidity without excessively weighing down the structure of the tape. The greater rigidity of the median fiber or of a few median fibers could even enable the use of thinner glass fibers as peripheral weft yarns and warp yarns and result overall in lighter joint tapes.

Patent application US 2007/0199271 describes a joint tape designed with a pulling means (pull strip), parallel to the longitudinal edge of the strip and that makes it possible to easily remove it from its support with a view to recycling the latter.

This document describes various embodiments of this pulling means.

In a first embodiment, represented in FIGS. 2, 3, 3A and 3B of D1, the pulling means is a strip bonded to the fiber mesh. The present invention differs from this embodiment by the fact that the reinforcing fiber is one of the longitudinal fibers of the woven fabric or knit fabric.

In a second embodiment, represented in FIGS. 6 and 6A and described in paragraph [0043], the pulling means may be formed by the longitudinal fibers themselves. It is indicated that the longitudinal fibers (630) may have a tensile strength greater than (FIG. 6) or equal to (FIG. 6A) that of the transverse fibers (625).

This joint tape is not however particularly suitable for being bonded in the corners. Indeed, in the first embodiment, the pulling means creates a zone of increased rigidity that is difficult or even impossible to fold. In the second embodiment, all the fibers have the same thickness and do not enable effective guiding of the strip in the corner.

Thus a need remains for a joint tape that is very particularly suitable for being bonded in the corners.

Consequently, one subject of the present invention is a joint tape, in strip form, formed by an open-mesh glass fiber warp knit fabric or woven fabric, said knit fabric or woven fabric comprising fibers parallel to the length of the strip (warp fibers) and fibers perpendicular to the length of the strip (weft fibers), said tape being characterized in that at least one glass fiber, referred to as reinforcing fiber, parallel to the length of the strip and located in the central zone thereof, has a linear density at least two times higher, preferably from two to ten times higher, in particular from three to eight times higher than the linear density of the other warp and weft fibers.

More particularly, one subject of the present invention is a joint tape, in strip form, formed by an open-mesh glass fiber warp knit fabric or woven fabric, said warp knit fabric or woven fabric being formed by

-   -   glass fibers parallel to the length of the strip, referred to as         longitudinal fibers, and     -   glass fibers perpendicular to the length of the strip, referred         to as transverse fibers,         said tape being characterized in that at least one of the         longitudinal fibers, referred to as reinforcing fiber, located         in the central zone of the strip, has a linear density at least         two times higher than the linear density of the other         longitudinal fibers.

The glass fibers used in the present invention are formed by thin individual filaments, generally provided with a size, assembled into a yarn of greater thickness.

The textile structures of the present invention do not encompass non-woven fabrics or weft knit fabrics, but only meshes, or woven fabrics, and warp knit fabrics, generally bound by a polymer binder or coating, preventing the glass fibers from sliding with respect to one another.

It is possible, in principle, to use any type of glass fibers, for example fibers made of E, C, R or AR (alkali resistant) type glass. The expression “glass fibers” used in the present invention also encompasses rock fibers manufactured from basalt. In particular, AR glass or E glass is preferred on condition that it is coated with a polymer coating, for example made of an EVA or SBR elastomer or made of an acrylic polymer, which protects against the alkalinity of the cement present in the plaster or mortar.

In one preferred embodiment of the present invention, all the glass fibers of the tape are coated with an elastomer.

The joint tapes of the present invention therefore contain at least two different types of fibers:

-   -   the reinforcing fiber or fibers, and     -   the normal, longitudinal or transverse glass fibers that are         thinner than the reinforcing fibers.

The linear density of the reinforcing fibers is generally between 30 and 300 dtex, preferably between 60 and 120 dtex.

The linear density of the other fibers is at least two times lower than those of the reinforcing fiber or fibers. It is preferably between 20 and 120 dtex, in particular between 30 and 70 dtex.

The joint tapes of the present invention generally have a width of between 30 mm and 80 mm, preferably of between 45 mm and 55 mm. They are produced in the form of an endless strip and are packaged in rolled-up form.

The reinforcing fibers, when there are several thereof, are all found in the median zone of the strip. This median zone extends over at most 10% of the width of the joint tapes of the present invention.

In one embodiment of the present invention, the joint tape comprises a single continuous reinforcing fiber, preferably located on the median line of the tape.

In one particularly advantageous embodiment of the present invention, the joint tape comprises two reinforcing fibers, adjacent to one another. The adjective “adjacent” does not mean here that the two reinforcing fibers are in contact with one another, but simply means that the two reinforcing fibers are neighboring, that is to say are not separated by one or more thinner fibers.

The normal glass fibers, thinner than the reinforcing fibers, may all have the same thinness. In another particular embodiment, the transverse fibers are thinner than the longitudinal fibers, which facilitates the longitudinal folding of the joint tapes.

The joint tapes of the present invention have an open-mesh structure. The meshes must be large enough to allow the passage of the plaster or mortar applied to the plasterboards and other construction elements to be joined. They may be of square shape, in the case where all the glass fibers are equidistant, or else have a rectangular shape, in the case, for example, where the weft fibers are spaced further apart from one another than the warp fibers.

In order to be free of these shape considerations, the size of the meshes is expressed in the present invention by means of the equivalent diameter, which is equal to the diameter of the circle of the same surface area as the opening in question. Thus, a square mesh having sides of X cm (surface area of X² cm²) has an equivalent diameter equal to 2(X²/π)^(1/2) cm.

The mean equivalent diameter of the open meshes of the joint tapes of the present invention is preferably between 2 mm and 7 mm, in particular between 3 mm and 6 mm.

The joint tape preferably comprises, on one of its faces, a self-adhesive coating, generally a pressure-sensitive adhesive (PSA) coating.

For easy application of the tape, the latter must have a sufficient initial tack in order to adhere by simple contact/pressure to a clean and dry wall and in order not to become detached under the effect of its own weight. As is known, this tack must not however exceed a certain value so that the tape remains easy to peel and reposition.

The adjustment of this adhesive strength is part of the general knowledge of a person skilled in the art who will know how to choose the nature and the concentrations of the various ingredients of the pressure-sensitive adhesive (such as the polymers, the tackifying agent, fillers, etc.) or else the geometry or the thickness of the PSA layer.

Pressure-sensitive adhesives that can be used in the present invention are known. They may be deposited in the form of a liquid composition based on an organic solvent or on water (latex) or else they may be thermofusible polymers, that is to say polymers of low molecular weight that, in the melt state, have a low enough viscosity to spread out in an appropriate manner.

The PSAs are generally based on an elastomer resin that may contain an agent that increases the tack (tackifying agent).

The polymer resin is conventionally selected from acrylic resins, butyl rubber, ethylene/vinyl acetate (EVA) copolymers, natural rubber, vinyl ethers, and styrene-based block copolymers such as styrene-butadiene-styrene (SBS), styrene-ethylene/butylene-styrene (SEBS), styrene-ethylene/propylene (SEP) and styrene-isoprene-styrene (SIS) copolymers.

EVA and the styrene-based block copolymers have the advantage of being thermofusible elastomers and can therefore be applied in the form of a solvent-free composition.

As explained in the introduction, the glass fiber strips of the present invention are used for joining together plasterboards or for joining plaster boards to other construction elements, in particular at the corners.

Consequently, another subject of the present invention is a process for jointing two flat construction elements forming, with respect to one another, an angle of less than 180°, said process comprising the application of a joint tape as described above, overlapping both construction elements so that the reinforcing fiber is superposed on the join line between the two construction elements.

One of the two construction elements is preferably a plasterboard. Particularly preferably, both construction elements are plasterboards. The angle that the two construction elements form is preferably an angle between 60° and 120° , in particular an angle close to 90°.

After applying the joint tape, the construction elements, including the joining zone, are generally covered with a uniform plaster coating.

FIGS. 1 and 2 represent two embodiments of the joint tape of the present application.

More particularly, FIG. 1 shows a portion of a joint tape 1 consisting of longitudinal glass fibers 2, parallel to the length of the tape, and transverse glass fibers 3 perpendicular to the length of the tape. The joint tape represented in this figure comprises nine longitudinal fibers, including one reinforcing fiber 4 thicker than the other eight fibers on either side of this central fiber. In this embodiment, the joint tape is intended to be folded so that the reinforcing fiber is in the angle formed by two plasterboards.

The joint tape represented in FIG. 2 is identical to that of FIG. 1 apart from the fact that it comprises not just one but two neighboring reinforcing fibers 4 having a thickness greater than that of the other longitudinal fibers. In this embodiment, the joint tape is intended to be folded between the two reinforcing fibers. 

1. A joint tape, in strip form, comprising an open-mesh glass fiber warp knit fabric or woven fabric, wherein the warp knit fabric or woven fabric comprises a glass fiber parallel to the length of the strip, referred to as a longitudinal fiber, a glass fiber perpendicular to the length of the strip, referred to as a transverse fiber, and a longitudinal fiber located in a central zone of the strip, referred to as a reinforcing fiber, wherein the reinforcing fiber, has a linear density at least two times higher than the linear density of the other longitudinal fibers.
 2. The joint tape as claimed in claim 1, wherein the tape comprises a single reinforcing fiber.
 3. The joint tape as claimed in claim 1, wherein the tape comprises two reinforcing fibers.
 4. The joint tape as claimed in claim 1, which has a width of between 30 mm and 80 mm.
 5. The joint tape as claimed in claim 1, wherein the reinforcing fiber has a linear density of between 30 and 300 dtex.
 6. The joint tape as claimed in claim 1, wherein the longitudinal and transverse glass fibers have a linear density of between 20 and 120 dtex.
 7. The joint tape as claimed in claim 1, wherein the open-mesh has an equivalent diameter of between 2 mm and 7 mm.
 8. The joint tape as claimed in claim 1, further comprising, on one of its faces, a self-adhesive coating.
 9. The joint tape as claimed in claim 1, wherein all the glass fibers are coated with an elastomer coating.
 10. A process for jointing two flat construction elements forming, with respect to one another, an angle of less than 180°, the process comprising applying the joint tape as claimed in claim 1 to the two flat construction elements, and overlapping both construction elements so that the reinforcing fiber is superposed on a join line between the two construction elements. 